Tapping knife



Aug. 21, 1951 J. l. HELLER 2,564,973

FREQUENCY MODULATED PRINTING Filed June 24, 1947 2 Sheets-Sheet 1 TIME gvwonfcm JOSEPH l- HELLER Aug. 21, 1951 HELLER I 2,564,973

FREQUENCY MODULATED PRINTING Filed June 24, 1947 g SheiEi-Sheet 2 UOSEPH LHELLER mama. 2i. I a

umrso STA-rs s PATENT orrics rumour-mar uonum'mn rnm'rm Joseph I. Heller, Brooklyn, N.

' mnesne assignments, to Marcel Wallace, doing business as Panoramic Laboratories, East Port Chester, Conn.

Application June 24, 1941, Serial Ne. 750,701

' strained to trace desired insignia or characters,

17 Claims.

record receiving surface.

One system of the above character to which my invention has particular application is disclosed in an application for U. 8. Patent Serial No. 729,378, filed February 18, 1947 in the name of M. Wallace, and entitled Stratograph, that application being assigned to a common assignee with the present application. By virtue of the invention of the present application it is feasible to transmit in the system described in the aforementioned application of M. Wallace, Serial No. 729,378, information from each source of telemetric data, which, being recorded in the form of printed letters, insignia. or characters of any desired type, is susceptible of ready interpretation at the recorder, the said printed letters, insignia or characters being superimposed on the telemetric data otherwise transmitted.

As an example of one use or application of the present invention information concerning the identity of a telemetric transmitter may be superimposed on a telemetric record, in terms of printed letters rather than in terms of coded interruptions of a carrier. 'As an example of a further such use or application, the superimposed characters may themselves have telemetric significance; so, where frequency of a transmitted carrier is interpretable as altitude of an aircraft, characters superimposed on the altitude representative, record may themselves be representative of hearing or range, of the transmitting aircraft. The invention is, of course, susceptible of still further uses and applications, which will readily suggest themselves to those skilled in the pertinent art.

Briefly described, I carry out my invention by applying controlled deviations of the frequency of a carrier, or deviations which occur in accordance with a predetermined law of time variation, the mean or average value of which is representative of a telemetric quantity, the deviations being controlled in respect to both timing and extent insuch manner that a facsimile recorder,

which is adapted and arranged to provide marks on a record receiving surface corresponding in lateral positions with received frequencies, is conas the transmitted frequency slowly varies, which are superimposed on the telemetric record, and serve to impart further information in conjunction therewith.

Accordingly, it is an object of the present invention to provide a system of telemetric transmission and reception, which envisages the possibility of superimposing desired insignia or characters on the telemetric record.

It is a further object of the invention t provide a system of transmitting telemetric data in terms of the average value of a transmitted carrier, further information of any desired nature being superimposed on the telemetric data in terms of deviations of the average value of the transmitted carrier.

It is still a further object of the invention to provide a telemetric system comprising a facsimile type recorder for recording values of a telemetric quantity, and for further recording characters of any desired type for conveying information supplementary to the telemetric data, the latter characters being superimposed on the telemetric record.

The above and still further features, advantages and objects of my invention will become apparent upon consideration of the following detailed description of a specific embodiment of y invention, especially when taken in conjunction with the accompanying drawings, wherein:

Figure 1 represents an embodiment of a telemetric transmitting station, in accordance with the invention; I

Figure 2 is a functional block diagram of a receiving and recording station in accordance with the invention;

Figure 3 is a plot of values of a telemetric quantity having indicia superimposed thereon, and indicating the character of the record provided in accordance with the present invention;

Figure 4 is an enlarged representation of a character transmitted in accordance with the invention, and analyzed in accordance with its constituent elements; and

Figure 4b is a plot of a cam outline required a Proceeding now with a detailed description of Y the invention, the circuit assembly I represents a conventional type of tunable transmitter-oscillater which may be tunable over any selected band of frequencies, say from 148-152 mc., in response to variation of capacity enforced upon tuning condenser 2 of the oscillator. Thecon- .than is directly generated thereby.

2,584,978 3 4 denser 2 may be tuned in response to mechanical the latter. The spacing between the various motion of an aneroid cell 3, the latter motion spring leads is so selected with respect to the curring in response to variations of atmospheric differences of radii of the peripheral sectors 0 pressure, as the pressure external to the cell varies that as the cam follower la follows the peripheral from that appropriate to sea level to that appro- 5 sectors 6 of cam 4, from a sector of minimum priate to an altitude of, say, 10,000 feet. The band radius to a sector of maximum radius, by succesof frequencies selected for operation is arbitrary. sive steps. the spring lead 1 contacts first none of as is also the range of frequencies and the corthe spring leads lb, and then contacts with the responding range of altitudes. It will be realized, lowermost of leads lb, the latter on the next stcp moreover, that the'condenser 2 might be varied 6 contacting with the next succeeding lead lb in respect to capacitance by measuring instruand so on until for the sector 8 of greatest radius ments other than an aneroid cell, in known manall the leads 1b are in contact. her, and hence that the transmitter-oscillator I By virtue of the fact that lead 1 is grounded,

mi t be adapt d for transmissi ns of si nals and that the condensers a are connected one in a frequencies ep ta ve bro y 0! y series with each of the spring leads lb, and thence sired telemetric or measurable quantity. While t common lead c, the condensers 9 may be I v disclosed the Preferred embodiment f my connected in selective plurality in parallel across invention 81$ pp to altitude mmurements. the oscillator tuning condenser 2 of the transand have chosen to specify a ra of altitudes mitter I, and hence may be utilized for producing Bn fl 0f Correspondin! fr q nclea y Way selected increments of deviation of the transo e a p the invention 18 not limited to such mitted frequency which conform with the radii'of' a I101 to s 59961110 application, 88 will the successive peripheral sectors I of the cam 4. pp as the description p ee Summarizing briefly theoperation of th ap- It will further be realized, that while I have paratus m t t m mg 1 f th drawings. disclosed the oscillator i as directly coupled with and which has n heflfibefqrg described 1 at a t s antenna. abufler amplifier and/0r detail, the transmitter "transmits signals at a a p w amplifier ay be t rpos d. f desi frequency bearing a dennltereiation to the altiin accordance with principles well understood in tude of the t tt ,gr t gt 'm u the art 01 radio communicfltmnand that jected to further frequency'lieviations centered the output Of 08011181401 I may be heterodyned 101 bout the mean or altitude fretransmission at a different value of frequency quency by means of th cam operated switching arrangement comprising cam I and trimmer condensers 9. It will of course be realizedthat in the practice of the present invention a plurality of aircraft (not shown) will normally be located in the vicinity of a ground station at any particur time, and that all such aircraft being similarly equipped, will simultaneously provide transmissp re; the characterabove described, the trans- 4o'. "l'n issiofis:varying in mean frequency as the altifiiftudes of'the aircraft difler in value, and each aircraft-transmitting timed deviations of a character For purposes of simplicity in the present exposition, the oscillator i is illustrated as transmitting directly, and may be considered to be mounted in an aircraft, or other elevated body, as desired, in which event the frequency of transmission will be at all times representative of the altitude of the body, and as the altitude of the body varies, so also will the frequency of trans mission of the associated transmitter l'-vary.

The transmitter I may be caused todeviate from its mean frequency of operation as determined by its altitude, by introducin'g into; the Egfgfifigggf character the cam wheel 1x5 2323; giig gi ggg i g gggfi" 7 Suitable apparatus for interpreting, translating and recording transmissions from the various capacity provided by condenser 2 and which deviv ates the transmitted frequency of the transmitter aircraft locate? adjacent ground station or to such extents, and at such times, as to landing field, is illustrated in Figure 2 of the vi e at the receiver and recorder of e r nt drawingsthe character of the record made being sygtem recorded mama, superimpogld g illustrated in Figure 3. Reference is presently mam telemetric recrd S e ifi ally I provide a made to these figures in connection with the folc wheel 4 having a Suitably coded periphery lowing detailed description of a recording station and which may be rotated by clock 5 or its arranged in accordance with the present invenequivalent, slowly. The cam wheel 4 is formed withaseries of peripheral sectors, some of greater M the gmllnd I u ilize a frequency and m of 1esser di t t mean (huh scannin radio receiver which scans continuously A of the cam, but all preferably of equal angular the band of frequencies allocated to altitude extents peripherally about the cam. The radius r presentation, which, in the present example, of any of the cam sectors 6 may be selected from is constituted of the band 150-155 me. The reamong a predetermined number of successive ceiver itself pr s an nna an R. values of radius, increasing and decreasing in stage II, a mixer l2 and a local oscillator l3, the equal steps of distance with respect to the mean outputs of the local oscillator I3 and of the R. F. radius A. stage I I being applied to the mixer l2, wherein by The cam wheel 4 may be provided with a cam reason 01 heterodyning action, an intermediate follower 6a, of insulating material, which is conor diilerence frequency is generated, in a manner nected' as by means of a rivet 8b with a flexible well known per se in the art involving superspring lead 1, preferably having one end la bent heterodyne receivers, the said intermediate or in the shape of a V or a U, and secured at its other difference frequency being amplified in an interend to a terminal 8 of an insulating terminal mediate frequency amplifier ll, the output of board 8a. The terminal board la is providedyglth which is applied to an amplitude detector IS, the a-total of 9 additional terminals 8b.; "1 t out put of the latter being in turn amplified by being selected by way of example o Q, an amplifier l6. Theirequency scanning action, of which is secured a further springfllead' Ib ing hereinbefore referred to, is caused by varying the of successively shorter lengths, proceeding"i' from capacity values of tuning condensers l1, l8 and the initial spring lead 1, but otherwisesimilar to 76 Is, associated respectively with the R. F. stage II,

I mixer I2, and local oscillator l3, and which are continuously rotated, at a preferred rate of 7% R. P. S. by means of a motor 20, causing the receiver to be responsive in succession to each frequency in its operative band, and the scanning action to be periodicand indefinitely and cyclihas a magnitude dependent on the amplitude of incoming R. F. signals, being zero in the absence of such signals. The output of the amplifier I6 is utilized to control the output from a marker voltage generator 2!, the output of which may be applied to a marker 22. The motor 20, in addition to driving the frequency scanning condensers l1, l8 and I9 may be utilizedto drive in synchronism a cylindrical member 23, having a helical raised platen portion 24 secured thereto, which extends about the cylinder for a total of one turn, the one turn entirely encompassing the cylindrical member 23, and the pitch of the helical portion 24 being such as to provide an element of the helix for each position along the axis of the cylinder 23. The relative phasing of the motion of condensers l1, l8, l9 and the cylinder 23 is such as to cause the extremity 25 of helix 24 to be immediately adjacent to marker 22- when the receiver is tuned to its minimum frequency (148 me.) corresponding with zero altitude, and such as to cause the extremity 26 of the helix to be immediately adjacent the marker 22 when the receiver is tuned to its maximum frequency (152 me.) corresponding with maximum altitude (10,000 ft.).

Since the frequency characteristic of a conventional straight line-frequency variable condenser is generally of pyramidal shape, the frequency increasing linearly with rotor shaft motion for 180 and thereafter decreasing in a relatively linear fashion for the remaining 180 of rotation of the rotor shaft, while the scanning platen utilized in the preferred mode of practicing the present invention travels in only one direction, linearly with time, it follows that the platen must complete a cycle of rotation during one half cycle or 180 of operation of the condenserand while the frequency of the receiver is increasing, and that the receiver must be disabled, as by cam 3i and associated switch 30, during the remaining half cycle or 180 of rotation, while the frequency is decreasing to zero. The cam 30 is driven from the motor 20 in proper phase for the purpose, having a 180 dwell for closing the switch 30 and a further 180 dwell for opening the switch 30.

As a consequence, the condensers l1, I8 and I9 must travel at one-half the rotational velocity of the helical platen 24. To accomplish the proper relative speed between the condensers I1, l8 and I9 and the helical platen 24, the condensers may be driven directly from the motor 20, while the platen is driven from the motor 20 through a speed increasing gearing 29, which provides a speed change in the ratio 1:2. The recorder energizing circuit comprising marker voltage generator 2! is disabled during the undesired half cycle of condenser rotation by means of a switch 30, which is controlled by means of a cam 3| driven from the'mOtOr 20, or by some equivalent mechanism.

A time calibrated record receiving surface 21 is maintained between the platen 22 and the cylinder 23, and in contact therewith, and is fed at some contenient rate, say 6" per minute, by means of a clockwork mechanism (not shown). The record receiving surface 21 may be constituted of suitably chemically treated paper, of such character that passage of current therethrough will cause a mark to appear on the paper. In the present instance current is caused to flow through the paper 21 by applying voltage to the platen 22, the cylinder 23 and the helical member 24 being constructed of metal and grounded. as indicated at 28, to provide a path to ground for the record producing current. The paper 21 is maintained in conductive condition, preferably slightly moist, and is dried after recording, and is collected, by means of apparatusv which is known per se, and is accordingly neither illustrated nor described herein. Voltage is applied to the marker 22 by the marker voltage generator 2|, which in the present apparatus may be an amplifier having low internal impedance, and which is capable of supplying sufllcient current flow to produce clear sharp markings on the paper 21.

Since the transmitter oscillator I is tuned primarily by means of an aneroid cell 3, which'is intended to measure altitude, and since measurements of altitude by means of aneroid cells are inaccurate unless ambient atmospheric pressure is corrected for, I introduce into the tuning of the R. F. stage II, the mixer l2 and the local oscillator I3, a tuning correction. derived from an aneroid cell 55, located on the ground, the cell serving to determine capacitance values of trimmer condensers 5! associated with each of the tunable elements ll, l2 and I3. Accordingly, any modification of tuning at the transmitter l which is introduced solely by ambient atmospheric conditions is matched by a corresponding change in tuning at the receiver. No correction for ambient conditions isrequired aboard the aircraft, since the correction is introduced at the receiver. The receiver then actually measures the difference in pressure measurements as between airbome aneroid cells, as 3, and the receiver associated cell, as 55, rather than the absolute valve of the pressure measurement, as taken aboard the aircraft, variations due to ambient conditions balancing out.

While I have illustrated and described the present system in conjunction with a recorder which functions by transmitting current through chemically treated paper, and in which a helical scanning platen is employed, the present system lends itself to use with recorders of various types and operating upon various principles. For example, I may utilize a generator 2| which is capable of creating a disruptive spark or other electrical discharge from marker 22 to platen 24, through recording surface 21, in which case chemically treated paper may be unnecessary. Alternately, I may cause the marker 22 to vibrate mechanically in response to signal output from generator 2|, that output being of alternating character, and of high frequency (of theorder of 5000) and controlled by the output of the amplifier I6, in which case recording may be accomfed or actuated record receiving surface, and is caused to record in response to reception of signals. In operation, the receiver of Figure 2. as itseans periodically through its assigned frequency spectrum, transmits a signal to the marker voltagegenerator Ii upon scanning through any existing signal. The I. l". amplifier it, having a finite frequency response characteristic, passes signals during a predetermined finite sector of scan of the condensers H, "II and II, resulting in a mark on the record receiving surface 21 which has extremely small but finite length laterally of the paper. which appreciable response of the receiver to any given signal takes place in a function of the static and dynamic selectivity of I the receiver as well as of the amplitude of the received signal. Accordingly, it will be clear that for signals originating remotely -of the receiving station, and hence received at low amplitude, the lateral extent of recorded signal will be slight, whereas signals transmitted from positions adjacent to th receiving station will be received at considerably greater amplitude and will cause recorded signals of correspondingly greater lateral extent. Observation of the recorded signals will, accordingly. provide information not only as to precise altitudes. and of transmitter identity, but also an approximate indication of transmitter ran e.

In order that misleading indications of range shall not be provided. by reason of thejf angle of elevation of transmitters with respect to the ground station, it is essential that a receiving antenna be used which is truly omni-directfional and which does not discriminate between arriving from different axirnuthal or elevational angles. Such antennas are available in the art, and accordingly no specific preferred antenna system is illustrated or described.

Referringnow to Figure 3 of the drawings. there is illustrated a record, such as isi'provided .by apparatus arranged in accordance. with the invention, and applying to a single aircraft. The relatively heavy line 40 represents aircraft flying at an altitude of 6000 it, as read against the calibration lines ll, each of which corresponds with a frequency which represents a multiple of 1000 ft. of altitude, in with the indicia 42. The indicia AP are each formed of a series of 9 dots. properly displacedf'fone from another both laterally and longitudinally of the record receiving surface, and are formed in re sponse to frequency deviations of the transmitted carrier caused by the cam 4. Figure l;

Referring now to Figure 4a of the .drawings, there is exemplified a letter of the alphabet, P. as recorded by the system of my invention, considerably enlarged to present clearly its structural characteristics. It will be noted that the letter is transmitted in terms of nine distinct deviations of a mean value of a carrier, the latter being represented by the soli line 40, and that the letter is made up of nine tinct markings ll. While nine distinct frequency deviations have been utilized, less than that number might be utilized by providing less than nine levels or distinct steps on the cam l, a section of the periphery of which The actual period during-- is represented in Figure 4b. Alternatively more The number of discrete markings to be utilised 7g ter, tunable meansfor tuning said transmitterto.

in creating any given letter of the alphabet. on

the other hand, depends not at all on the number of trimmer condensers I which are utilized in the system. but depends entirely on the design of the cam. I have arbitrarily selected nine such markings to represent the letter P.

Likewise the units of frequency deviation utilined in the system involve a matter of choice only.

and 'a greater or a lesser deviation may be utilized in accordance with the desired height of the indicia; still further the lateral extends or .widths of the indicia depend upon the relative with a radial position of a cam sector, and the corresponding frequency positions or deviations of the recorded character and of the cam outline being identified in Figures 4a and 4b, respectively, by corresponding numerals. The position I is the normal position of the cam, about which deviations take place. whence the position 5 in Figure dd represents a value of altitude, in the present application and embodiment of the invention. During normal altitude transmissions, then. while no indicia are being transmitted the earn 4 is arranged to maintain five of trimmer condensers l in circuit, adding and subtracting wndensers as required for transmission of the indicia. to eifect slight incremental increases or decreases of mean Irequencye The outline of the cam l as illustrated in Figure 4 of the drawings need not correspond precisely with the actual outline of a working cam. By reason of the perpendicular sides or the cam sectors, as illustrated, some difllculty may be encountered by the follower in following the cam outline, and this will, in turn, introduce irregularities in the recorded indicia. In actual practice therefore the outlines of the cam sectors may be rounded very considerably to effect a smooth transition from one cam level to another. The

effect of this expedient is to introduce slight spaces along the time axis between the various of application for Patent Serial No. 729,378, filed February 18. 1947, it will be clear that any of the various species of recorder described and illustrated in that application may be utilized in the practice of my invention,- the specific recorder utilized involving merely a matter of choice.

While I have illustrated and described one specific embodiment of my invention, various modifications of the general arrangement and of details of construction may be resorted to without departing from the spirit and scope of the inventionas'defined in the appended claims.

WhatIcla-imanddesiretosecurebyletters Patent of the United States is:

1. A telemetric system comprising a transmittransmit a carrier signal at a frequency representative of a value of a measurable quantity, recorder means for recording values of saidmeasurable quantity in response to the frequency of said signal, and means for controllably deviating the tuning of said transmitter with respect to said frequency in accordance with a predetermined law of time variation representative of a printed character.

2. In a telemetric system having a tunable transmitter, a measuring device, means responsive to said measuring device for controlling the tuning of said transmitter to provide transmission at a first carrier frequency dependent upon the value of a measurable quantity as determined by said measuring device, a periodically frequency scanning receiver, a periodically line scanning recorder for Scanning a record receiving surface of'said recorder, means for synchronizing said space scanning with said frequency scanning, and means responsive to receipt of a signal by said receiver for causing said recorder to create a mark on said record receiving surface, the combination of means for further deviating the frequency of said transmitter from said first frequency in accordance with a time law of variation of frequency such as to provide recorded characters on said record receiving surface.

3. A system for transmitting characters comprising a tunable transmitter, a recorder having a periodically space scanning recording mechanism, a periodically frequency scanning receiver for receiving signals from said tunable transmitter and scanning in synchronism with the scanning of said recording mechanism, and means for deviating the frequency of said transmitter in accordance with a predetermined law of frequency variation with time, representative of a printed character, said recorder comprising means operative when said signals are received by said frequency scanning receiver during frequency scanning thereof for making a record representative of said carrier and of the deviations thereof, to reproduce said printed character.

4. A system for transmitting printed characters comprising a tunable transmitter tunable over a predetermined band of frequencies, a periodically line scanning facsimile recorder, a periodically frequency scanning receiver scanning periodically said predetermined band of frequencies, means for synchronizing the line scanning of said recorder with the frequency scanning of said receiver, means responsive to signal output from said receiver for actuating said recorder to make a mark, and means for varying the tuning of said said information bearing characteristic of said iary visually significant information, and means at said receiver for translating modifications of said information bearing characteristic of said signals into modifications of the visible indicachronizing operations of said tuning means and I of said recording member to provide correspondence between frequencies of received signals and lateral positions of said recording member, and means for varying the tuning of said transmitter in accordance with a predetermined law of time variation representative of a printed character.

6. In combination, a transmitter for transmitting signals to a remote receiver-indicator, said signals having an information bearing characteristic representing values of a measurable quantity, means at said receiver-indicator for translating tions corresponding with the content of-said auxiliary information.

7. In combination, a plurality of space separated transmitters foi transmitting information to a receiver-indicator common to said plurality of transmitters, means for controlling each of said transmitters to transmit signals having a characteristic identifiable in terms of the value of a measurable quantity, means for superimposing on said signals at each of said lurality of transmitters modifications of said characteristic determined in accordance with the space pattern of the elemental portions of a predetermined symbol, said receiver indicator comprising means for interpreting said characteristic of said signals in terms of visible indications of said values and reconstructions of said predetermined symbols.

8. In combination, a transmitter for transmitting signals to a remote receiver, means for varying a characteristic of said signals in accordance with the value of a quantity, means for further varying said characteristic of said signals in accordance with the space pattern of a symbol, and means associated with said receiver for translating said signals into an indication of values of said quantity superimposed on the space pattern of said symbol.

9. In combination, a signal transmitter, means for tuning said transmitter to transmit a carrier having a frequency in accordance with values of a measurable quantity, means for modifying'said tuning further in accordance with the space pattern of a symbol to provide frequency deviations of said carrier representative of said symbol,

10. In combination, a transmitter, means for tuning said transmitter to transmit a carrier within a band of frequencies continuously in accordance with values of a measurable quantity, means for modifying said tuning further in accordance with a tuning pattern determined by the space pattern of a symbol, means comprising a frequency scanning receiver scanning periodically over said band of frequencies for receiving signals provided by said transmitter and for translating said received signals into a plot against a time axis of values of said quantity and an associated reconstruction of the space pattern of said symbol.

11. In combination, a signal transmitter, means for modulating a characteristic of said signal in accordance with a first law of time variation of said characteristic, said first law corresponding with the time variation of a'measurable quantity, means for further modulating a characteristic of said signal in accordance with a timing pattern of a symbol, means for receiving said signals and for translating same into a plot against time of values of said measurable quantity and an associated reconstruction of the space pattern of said symbol.

12. In combination, a signal transmitter for area-,ovs

, transmitter for imposing on said signals transmitted thereby carrier frequency variations determined by the spatial configuration of a symbol,

'said' receiver being adapted and arranged for translating said characteristics offsaid si nals into a visual facsimile of said symbol located in juxtaposition to said visual indications of the said magnitude of said physical quantity.

13. In a system for transmitting telemetric a transmitter, measuring means for measuring the magnitude of a quantity, means responsive to said measuring means for tuning said transmitter to transmit a carrier having a frequency representaflve of said quantity, an auxiliary tuning means information and superposed printed characters,

for said transmitter for varying the frequency of said carrier with respect to said first mentioned frequency, and means for controlling said auxiliary tuning means in accordance with a predetermined timepattern representative of said printed characters.

14. The combination in accordance with claim 13 wherein is further provided a receiver for receiving said carrier and detecting the frequency thereof. and means for recording the variations or said frequency against a time base.

15. In a system for transmitting signals repre-.

. f of said carrier from said value in ac- ;with a time pattern representative of I16 characters.

18 The combination in accordance with claim 15 wherein is further provided a frequency scanning receiver for receiving said carrier, said fre quency scanning receiver scanning said predetermined spectrum periodically, a periodically line scanning recorder having a time fed record 're-.

ceiving surface and a line scanning marker scanning periodically across said surface, and means for actuating said marker for creating a mark on said surface in response to detection of said carrier by, said frequency scanning receiver.

17. In a system for transmitting signals representative of printed carriers superposed on telemetric information. a measuring device for meas-x uring the magnitude of a physical quantity, a primary tuning means for said transmitter, means responsive to said measuring device for setting said primary tuning means to effect generation by said transmitter of a carrier having a frequency representative of said magnitude, an auxiliary tuning means for said transmitter for varying said frequency, a mechanically actuated control for said auxiliary tuning means, said mechanically actuated control constructed and arranged for varying said auxiliary tuning means for v rying said frequency in accordance with a time pattern representative of said printed matter.

JOSEPH I. HELLER.

nan-mamas Crrnn The following references are 'of record in the file ofthispatent:

UNITED s'rs'rns rs'ra'n'rs Number Name Date 1,917,995 Polin July 11, 1933 1,929,241 Franklin Oct. 3, 1933 1,985,854 Finch Dec. 25, 1934 2,157,122 Dunmore May 9, 1939 2,173,741 Wise et al Sept. 19, 1939 2,210,903 Dunmore Aug. 13, 1940 2,468,803 Giflen Apr. 12, 1949 2,469,213 Shea May 3, 1949 

